Filter



Dec. 26, 1939.

' T. L. GENTER FILTER Filed July 27, .1936

3 Sheets-Sheet l INVEN'fOR -762000/1? Z Gen/er- ATTORNEY.

'T. L. GENTER Dec. 26, 1939.

' FILTER Filed July 27, 1936 3 Sheets-Sheet 2 INVENTOR. 7/)e0o0re Z.fen/er BY W ATTORNEY.

T. L. GENTER Dec. 26, 1939.

FILTER Filed .July 27, 1936 3 Sheets-Sheet 3 INVENTOR. flew are Z.Gerner W ATTORNEY Patented Dec. 26, 1939 UNITED STATES PATENT OFFICEFHITER Theodore L. Genter, Oakland, Calif.,' assignor to Oliver UnitedFilters Incorporated, San Francisco, Calif., a corporation of NevadaApplication July 27, 1936, Serial No. 92,780

6 Claims. 01. 210-200) This invention relates to filters of the disctype wherein filtration is effected under the influence of adifferential pressure and the cakeformed on the filter medium isdischarged by the aid'of a reverse pressure.

In the past it has been the practice to support the discs of a rotarydisc filter on a hollow central shaft and to discharge the filtratepassing through the filter medium through nipples or fittings connectingthe disc sectors to the shaft. This requires a large heavy shaft and isobjectionable for the reason that the effective filtering surface of thediscs is decreased. Also, it has been the practice to discharge the cakeformed on the filteringsurface of each disc simultaneously by the use ofa blow back or reverse pressure. The application of a reverse pressure,applied to the interior of the filter medium, causes the filter mediumto belly outwardly. It is common practice to space the filter discssufliciently far apart to permit cake building over the entire surfaceand on both sides of the discs, and then leave free space enough betweentwo adjacent cakes to permit them to be discharged and fall freely intothe scroll or hopper underneath the filter shell. However it frequentlyhappens that during the cake discharging operation adjacent cakes archover or twin, thereby causing difiiculty in properly discharging thefilter.

One of the objects of this invention is the provision of a methodwhereby the cakes formed on adjacent disc sectors may be dischargedalternately rather .than simultaneously, thereby not only preventing thetwinning of cakes, but at the same time permitting a closer spacing ofthe discs, with a corresponding increase in filter area.

It is common practice to prevent the filter discs fromwarping out ofline (i. e., out of a plane at,

' right angles to the center shaft) by stiffening the entire series ofdiscs by means of longitudinal rods, clips, clamps, or spacers.

Another object of this invention is the provision of a number oflongitudinal members, each performing a threefold duty: (a) a supportfor the features, some of which with the foregoing will be set forth atlength in the'following description where that form of the inventionwhich has been selected for illustration in the drawings accompanyingand forming a part of the present specification is outlined in full. Insaid drawings, one

form of the invention is shown, but it is to be understood that it isnot limited to such form, since the invention as set forth in the claimsmay be embodied in a plurality of forms.

Referring to the drawings:

Figure 1 is a side elevation, partly in section, of a disc filterembodying the objects of my invention. 0

Figure 2 is a vertical section taken on the line 2-2 of Figure 1.

Figure 3 is a vertical section taken on the line 33 of Figure 1.

Figure 4 is a detail view of the coupling for connecting the discsectors to the filtrate manifolds.

ferential pressure for eflecting filtration and for as applying areverse pressure alternately to adjacent disc sectors.

Figure 7 is a section taken on the line of Figure 6.

Figure 8 is a section taken on the line 8-8 of Figure '7 i As best shownin Figures 1, 2, and 3, my invention comprises a shell or casing l ofgeneral cylindrical form and provided with outwardly dished heads 2 and3. minates in a scroll compartment 4, reinforced by spaced vertical webs10, while its top is closed by a cover 5 having a peripheral flange 6adapted to register with a peripheral flange I formed around be securedto the casing l by bolts passing through the peripheral flanges 6 and"I, and a gasket 8 may be placed between the peripheral flanges 6 and Ito form an air-tight seal. In order to enable the The bottom of thecasing l terp the upper part of the casing l. The cover 5 may. 40

cover 5 to be lifted from the shell I, it is provided with ears 9 havingopenings ll therein, through which a hoisting hook may be inserted. Thecover 5 is placed at the maximum height above the horizontal center lineof the shell or casing I, to

permit removal of the cradle with 75% of the sectors at one operationand at the same time to provide the cover 5 with a minimum area.Communicating with the scroll chamber 4 is a pulp or slurry inlet l2 anda cake discharge outlet 13, and disposed within the scroll compartment 4is a false bottom or pan |4 provided with openings I5. The scrollcompartment 4 together with the pan |4 defines a chamber l6 throughwhich the pulp or slurry entering the inlet l2 must pass in order toreach the main chamber H of the casing I. Supported on a shaft I8disposed within the scroll compartment 4 immediately above the pan I4,is a scroll l9. The left hand end of the shaft I8 is journaled in aflanged bearing 20 carried by a plate 2| which in turn is secured inregistration with an opening 22 formed in the dished head 2. The outerend of the shaft I 8 is enclosed by means of a flanged cap 23 bolted orscrewed to the flanged bearing 20. The right hand end of the shaft |8passes through a stuffing box 24 secured to the dished head 3, and isjournaled in a bearing 25. The outer end of the shaft is provided with asprocket 26 for connecting it to any suitable driving mechanism. Formedintegrally with the dished head 2 is a bracket 21, and supported on thisbracket is a bearing 28. Secured to and extending through the dishedhead 2 substantially in line with the axis of the casing is a stuflingbox 29. Formed integrally with the dished head 3 is a bracket 3| adaptedto support a bearing 32. Secured to and extending through the dishedhead 3 in line with the axis of the bearing 28 and stufiing box 29 is astuffing box 33. The casing is provided on one side with an inspectionport 34 (Figure 2) and with a vent pipe 35 (Figure 1).

Rotatably disposed within the casing is a frame or cradle adapted tosupport a plurality of spaced sectionalized filter discs. The cradlecomprises a hollow central shaft 36, the axis of which is coincidentwith the axis of the bearings 28 and 32. symmetrically disposed aboutthe hollow shaft 36 and in spaced relation thereto are four ellipticallyshaped filtrate manifolds 31, 38, 39 and 4| (Figures 1 and 3). Thesemanifolds are held in spaced relation with respect to the hollow shaft36 by means of radius rods 42. The left hand ends of the filtratemanifolds 31, 38, 39 and 4| communicate by means of radially extendingpipes 43' with a flanged casting 44 welded or otherwise secured to theleft hand end of the hollow shaft 36. Each of the filtrate manifolds 31,38, 39 and 4| is provided along its length in spaced relation withfittings or couplings 45 and with a boss 46 provided with a threadedstud 41. As shown in Figure 4, the coupling 45 extends to the left,while the boss 46 with its threaded stud 41 extends to the right.However, it is to be noted from an inspection of Figures 1 and 3 thatthe relative positions of these members are reversed in every alternateset of these members along the length of the filtrate manifolds. Thereason for this reversal of members will be set forth in connection withthe description of the operation of the filter. Secured to the hollowshaft 36 are a plurality of sets of saddles or U-shaped clips 48, therebeing four clips to each set, symmetrically disposed about the shaft 36.Each of these sets of clips lies in a common plane with itscorresponding fitting 45 and threaded stud 41. The frame or cradle thusformed by the hollow shaft 36 and the filtrate manifolds 31, 38, 39 and4| constitutes a support for a plurality of spaced sectionalized filterdiscs. Each disc consists of four sectors, 5|, 52, 53 and 54. Eachsector is seated at its inner end or apex on one of the saddles orU-shaped clips 48, and is secured at its periphery at one end to thethreaded stud 41 by means of an apert-ured lug 55 and at the other endto the fitting or coupling 45 by means of a complementary fitting orcoupling 56 welded or otherwise secured to the sector. As shown inFigure 5, the couplings 45 and 56 constitute a union and are secured insealed relation by means of a threaded stud 51 welded to the coupling 56and a nut 58 threaded on the stud 51 and adapted to be seated in adepression 59 formed in the coupling 45. In order to obtain an air-tightconnection between the couplings 45 and 56, a gasket 6| is interposedbetween their engaging surfaces. The sectors may be of any well-knownconstruction such as for example indicated in Figure 5. As shown in thisfigure, the sectors comprise a drainage screen 62, to the opposite sidesof which is secured a supporting screen 63. The peripheral edges of thisstructure are secured to a frame member 64 provided on each side withperipheral channels 65. The filter cloth is disposed over the outerfaces of the supporting screen 63 and secured at its peripheral edgeswithin the channel 65 by means of a caulking strip 66.

From an inspection of Figure 3, it will be noted that the interior ofthe sector 5| communicates through the couplings 45 and 56 with thefiltrate manifold 38, and that in the same manner the sector 52communicates with the filtrate manifold 39, the sector 53 with thefiltrate manifold 4|, and the sector 54 with the filtrate manifold 31.The sectors 5| of each disc are in alignment, and therefore constitute alongitudinally extending row of sectors. Since Figure 3 is a sectiontaken on the line 33 of Figure 1, it will be noted that the disc shownin Figure 3 and made up of the sectors 5|, 52, 53, and 54 would be thetwelfth disc of the series of discs making up the filter. The disc shownin Figure 3 is therefore an even numbered disc. The connection betweeneach of the sectors of the even numbered discs with their respectivefiltrate manifolds is shown in Figure 3, while the connection betweenthe sectors of the odd discs and their respective filtrate manifolds isjust the reverse of that shown in Figure 3. In other words, if it wereto be assumed that the disc shown in Figure 3 is an odd numbered disc,the sector 5| would communicate with the manifold 31, the sector 52 withthe manifold 38, the sector 53 with the manifold 39, and the sector 54with the manifold 4|. This sequence of connections permits the sectorsto be discharged alternately, as will be more fully described inconnection with the operation of the filter.

Referring now to Figure l, the right hand end of the hollowccentralshaft 36 terminates in a flanged collar 1|. Extending through thestuffing box 33 is a solid stub shaft 12, the left hand end of whichterminates in a flanged collar 13 adapted to be secured to the flangedcollar 1| by means of bolts. The shaft 12 is journaled in the bearing 32and is secured at its extreme right hand end to a ring gear disposedwithin the gear housing 14 carried by the bracket 3|. It will thereforebe seen that the hollow shaft 35 together with its disc assembly may berotated by connecting the rin gear within the housing 14 to any suitabledriving mechanism.

Extending through the bearing 28 and the stufling box 29 is a cored stubshaft 80. The right hand end of the shaft terminates in a flange 8|adapted to be bolted to the flanged casting 44. The casting 44 isprovided with four valve member 86 by means of bolts 81, and the valvemember 86 is provided with four chambers 88, 89, 91 and 92, incommunication respectively with the' passageways 82, 83, 84, and of theshaft 80. Each of the chambers 88, 89,9I and 92 is provided with a valveseat 93 adapted to receive a valve 94 carried by the valve stem 95. Eachof the valve stems 95 operates through a sleeve 96 provided with aflange 91 adapted to be secured over the left hand ends of the chambers88, 89, 9I and 92. In order to maintain these chambers air-tight, thesleeves 96 are provided with stufling boxes 98. The valve member 86 isadapted to rotate within a valve housing IOI sealed to the valve memberby means of stufiing boxes I02 and I83. The valve housing IN is providedon its lower side with a filtrate outlet I84 and on its upper side withan inclined cylinder I85 adaptedto accommodate a hollow piston I06. Theupper end of the hollow piston I86 is secured to a stem I81 arranged topass through a stuffing box I88 formed in the plate I89 covering andsecured to the upper end of the cylinder I85. The port III formed on oneside of the cylinder I85 is adapted to registerwith a complementary portII2 formed in the piston I86, when the piston is in its lowermostposition. As the piston is raised, it closes the port III. The oppositeside of the cylinder I85 is provided with a key II3, the inner end ofwhich is adapted to engage a slot II4 formed in the piston I86, in orderto prevent the rotation of the piston within the cylinder. Extendingupwardly from the cover plate I89 is a bracket H6 and a lug II1. Pivotedto the lug H1 is a lever II 8 provided with a notch H9 and a notch I20.The free end of the lever H8 is urged in a counter-clockwise directionby means of a spring loop I2I Pivoted to the bracket H6 is a controllever I22 provided with a pin I23 adapted to be received in eitherthenotch II9or the notch I28. The intermediate end of the control leverI22 is adapted to be received in the bifurcated end I24 of the stem I01,and to engage on its upward motion a pin I26 passing through thebifurcated end of the stem. A collar I26 is secured to the stem I81intermediate its ends and is adapted to support a spring I 21 which inturn supports a washer I28 slidably disposed on the stem I81. The pistonI06may be designated as a blow bridge and in Figure 7 is shown in itslowermost position urged in engagement with the valve.

member 86 by the spring I21 so that its port H2 is in registration withthe port I I I. The port Ill may be connected to a source of fluidpressure such as either air-or flue gas. When it is desired to c ose theport III, the lever H8 is moved slightly in a clockwise direction sothat the pin I23 may be released from the notch .I I9. Control lever I22is then moved upwardly until the pin I23 engages the notch- I28. Thelever 122 in moving upwardly engages the pin I25, thereby causing theblow bridge or piston I86 to move upwardly. Communication between thevalve housing I8I and the chambers 88, 89, 9| and 92 is established bymeans of peripheral ports I29 formed in the valve member 86. It

will aso be noted that the peripheral ports I29 serve to establishcommunication between the lower end, of the blow bridge or piston I06and. the chambers '88, 89, 9I and 92.

is fed to the casing I through the pulp or slurry intake I 2. The pulpor slurry passes through the chamber I6, through the openings [5 formedin the pan I4, and into the main chamber I1. The casing I is compietelyfilled with slurry and the slurry maintained therein undersuperatmcspheric pressure by means of aslurry pump (not shown). Duringthe filtration operation the blow bridge or piston I86 is held in itsuppermost position so that the port III is closed and each of the valves94 is made to assume a fully open position. The only time that thevalves 94 are closed as shown in Figure 7 is when it is desired torender inoperative all of the sectors communicating with any one of thefour filtrate manifolds 31, 38, 39 and 4|, and as a rule this isnecessary only when a leak has developed in one or more of the sectorsdue to a break in the filter cloth. The differential filtering pressurecaused by atmospheric pressure within the sectors and thesuperatmospherie pressure at which the pulp or slurry within the casingI is maintained causes the liquid content of the slurry to pass throughthe filter medium, through the filtrate manifolds, through the chambers88, 89, 9| and 92, and out through the filtrate outlet I84. The solidcontent of the pulp or slurry is deposited as a cake on the outersurface of the filter medium. When fi tration has progressed to a pointwhere an econc-mical rate of filtration is no longer being obtained,further filtration is stopped by shutting off the slurry pump, openingthe return to the supply tank, and blowing back the excess from the bodyof the filter in the usual manner. A free space must of course alwaysremain between adjacent cakes, for if adjacent cakes were permitted totouch, an unbalanced condition would result, causing damage to thefilter.

To discharge the cake formed on the sectors, the casing I is drained ofslurry and then the shaft 36 is rotated by meansof thering gear withinthe housing 14 at a rate of about one revolution per minute. The portIII is opened by moving the blow bridge or piston I86 to its lowermostposition, and the port I I I is connected to any suitabie source offluid pressure, preferably air or gas. Upon the rotation of the valvemember 86 which rotates with the hollow shaft 36, the fluid entering theport III passes through the lower end of the blow bridge or piston I86and successively passes through each of the filtrate manifolds 31, 38,39 and 4|. From these filtrate manifolds the fluid passes through thecouplings 45 and 56 to the alternate sectors connecting with each of thefiltrate manifolds.

From an inspection of Figure 6, it will be noted that since the cylinderI85 is inclined at a slight angle to the horizontal plane passingthrough the axis of the filter, the blow back or reverse current offluid used indischarging the cakes from the sectors is successivelyintroduced into the passageways 82, 83, 84 and 85 formed in the shaft 88before the corresponding filtrate manifolds assume a horizontalposition. However, there is-a certain time interval required for thefluid to pass from the valve to the filtrate manifolds, and bythe timethe fluid has reached the manifold which has been placed incommunication with the blow bridge, that particular manifold will havereached a substantially horizontal position. In other words, by suitablylocating the blow port, the disc sectors may be inflated when themanifold to which they are connected is in a horizontal position.

Referring now to Figure 3, it will be seen that the manifold 38 hasassumed a substantially horizontal position and in this position theblow back or reverse fluid current will enter each of the sectorscommunicating therewith. At this stage of the cycle, the sectors 5| ofthe even numbered discs and sectors 52 of the odd numbered discs will bedischarged. When the filtrate manifold 31 (due to the clockwise rotationof the disc assembly) has assumed a horizontal position, the sectors 5|will of courseoccupy the lower right hand quadrant and in this positionthe sectors 5| of the odd numbered discs and sectors 54 of the evennumbered discs will be discharged. It is to be noted that at this stageof the cycle all of the sectors 5| of both the even and odd numbereddiscs will have been discharged. When the manifold 4| has been rotatedto a horizontal position, the sectors 54 will occupy the lower righthand quadrant and at this point the sectors 54 of the odd numbered discsand sectors 53 of the even numbered discs will be discharged. When thefiltrate manifold 39 assumes a horizontal position, the sectors 53 willoccupy the lower right hand quadrant and at this stage of the cycle thesectors 53 of the odd numbered discs and sectors 52 of the even numbereddiscs will be discharged. By discharging at one time the alternatesectors in the row of sectors occupying the lower right hand quadrantand the intermediate sectors occupying the upper right hand quadrant,contact between the cakes formed on adjacent sectors is prevented and afree vertical drop of the cake is permitted. In this connection, it isto be noted that the scroll compartment 4 has been disposed slightly tothe right of a vertical plane passing through the axis of the filter sothat the discharged cake may drop substantially vertically into thescroll compartment. By discharging the cake in this manner the centralshaft does not form an obstruction to the cake dropped from the sectionin the upper right hand quadrant, and the right hand filtrate manifold,due to its downward movement, tends to force the cake discharged fromthe sectors in the lower right hand quadrant into the scrollcompartment.

Although each of the discs of the filter above described has beendivided into four sectors, any other desired division may be made. As amatter of fact, even if the discs are not sectionallzed, they can bealternately discharged by the use of a suitable valve and filtratemanifold arrangement.

A filter constructed and operated as above described has the followingadvantages:

By connecting the sectors to filtrate manifolds located peripherally ofthe filter discs and conveying the filtrate away through these manifoldsrather than through the central shaft, it is possible to use a. muchsmaller central shaft and therefore to increase the effective filteringarea of the sectors. Furthermore, by forming the connections between thesectors and the filtrate manifolds at the periphery of the discs ratherthan adjacent the central shaft as has been the practice heretofore, abetter connection can be made, for obviously there is more room in whichto work, and the sectors can be more readily detached from the cradleformed by the filtrate manifolds'and the central shaft.

The disc assembly including the central shaft and the filtrate manifoldsmay be readily disconnected from the rest of the filter and removed fromthe casing.

The automatic valve permits one or more of the filtrate manifolds to beput out of operation without impairing the operation of the othermanifolds and also enables the sectors to be alternately discharged.

Heretofore all of the cakes formed on the discs of a pressure filterhave been discharged at the same time, and consequently it has beennecessary to provide a scroll capable of taking care of the entire load.In a filter embodying the'objects of my invention, wherein the sectorsare alternately and successively discharged, the scroll is required tohandle only one-fourth of the entire load at any one time and thereforemay be made much lighter. The alternate discharge of the sectors permitsthe use of a shorter filter and a smaller scroll and at the same timeprevents contacting of cakes formed on adjacent sectors during thedischarge period.

I claim:

1. A filter comprising: a casing; a shaft supported Within said casing;a plurality of filter discs supported in spaced relation along saidshaft, each of said discs being formed by a plurality of sectors andeach sector of each disc being in alignment with the correspondingsectors of the other discs, so that there are as many longitudinallyextending rows of sectors as there are sectors in eachdisc;longitudinally extending filtrate manifolds associated with saidsectors, there being as many manifolds as there are rows of sectors;means for connecting each of said manifolds to the alternate sectors inone row and to the intermediate sectors of an adjacent row; and anautomatic valve associated with said manifolds for successivelysubjecting said manifolds to a reverse pressure.

2. A filter comprising: a casing; a shaft supported within said casing;a plurality of filter discs supported in spaced relation along saidshaft, each of said discs being formed by a plurality of sectors andeach sector of each disc being in alignment with the correspondingsectors of the other discs, so that there are as many longitudinallyextending rows of sectors as there are sectors in each disc;longitudinally extending filtrate manifolds associated with saidsectors, there being as many manifolds as there are rows of sectors;quickly detachable couplings for connecting each of said manifolds tothe outer peripheries of the alternate sectors in one row and theintermediate sectors of an adjacent row; and an automatic valveassociated with said manifolds for successively subjecting each of saidmanifolds to a reverse pressure.

3. A filter comprising: a casing; a shaft supported within said casing;a plurality of filter discs supported in spaced relation along saidshaft, each of said discs being formed by a plurality of sectors andeach sector of each disc being in alignment with the correspondingsectors of the other disc, so that there are as many longitudinallyextending rows of sectors as there are sectors in each disc; filtratemanifolds extending longitudinally between and substantially at theperipheries of said rows of sectors; means for connecting each of saidmanifolds to thealternate sectors in one row and to the intermediatesectors of an adjacent row; and an automatic valve associated with saidmanifolds for successivelysubjecting each of said manifolds to a reversepressure.

, 4. The method of discharging a filter wherein a plurality ofsectionalized discs are mounted in spaced relation along a common shaftand wherein the corresponding sections of each disc are in alignment sothat there are as many rows of sections as there are sections in eachdisc, comprising: successively subjecting groups of sections consistingof alternate sections in one row and intermediate sections in anadjacent row, to a reverse fluid pressure. p

5. The method of discharging a filter wherein a plurality ofsectionalized discs are mounted in spaced relation along a common shaftand wherein the corresponding sections of each disc are in alignment sothat there are as many rows of sections as there are sections in eachdisc, comprising: subjecting not more than every other section in anygiven row to the action of a reverse fluid pressure at one time.

6. The method of operating a filter wherein a plurality of filterelements are mounted in spaced relation along a common shaft,comprising: first discharging the alternate filter elements and thendischarging the remaining intermediate filter elements. I

THEODORE L. GENTER.

